Git: How to diff two different files in different commits?

Question

I have a repository where a number of files have been renamed from .html to .php and further edited in a number of commits since my last pull. Using git diff to shows all the html contents removed and all the php content added. Is there a neat way to have git diff detect the renames (something like git log --follow does), or directly compare different filenames across different commits (something like the solution in Git: How to diff two different files in different branches? , but for commits)?

This does the trick, thanks, please convert to an answer so I can accept. (It is at the individual file level, unfortunately, but I can do what needs to be done with it for now.) — Steve Kroon, Mar 27 '17 at 10:04
@dave: that does not actually matter. Git normally *detects* renames (rather than recording them) by doing tree comparisons. That, however, requires that you diff two complete trees, not two specific files within the tree. — torek, Mar 27 '17 at 15:19

Eugene Kaurov · Accepted Answer · 2018-03-09T16:25:47.017

32

You can always compare 2 files in 2 different commits:

git diff commit1:file1_path commit2:file2_path

edited Mar 09 '18 at 16:25

answered Mar 08 '18 at 17:38

Eugene Kaurov

2,356
28
39

1

Answers with just code get flagged as 'Low Quality Posts', try explaining your answer a little to avoid it being deleted. – piman314 Mar 08 '18 at 19:42
@ElpieKay provided this answer as a comment on my question a year back - tagging him here to provide it as an answer. If I don't get a response from him in a week, Eugene, ping me here and I'll accept your answer. – Steve Kroon Mar 27 '18 at 23:05
@SteveKroon It would be already 3 weeks tomorrow since the time of your comment. I appreciate ElpieKay input, he really added good commented, but looks like he is not available. If you like, feel free to accept my answer/ – Eugene Kaurov Apr 16 '18 at 18:17

Jacob Kopczynski · Answer 2 · 2020-10-19T20:44:46.373

As said previously, the format needed is:

$ git diff commit1:file1_path commit2:file2_path

But there are a couple gotchas:

XXX$ git diff file1_path commit2:file2_path

This will not work, even if file1_path is in HEAD; if you want to specify a commit for one file you must specify it for both. This will attempt to interpret "commit2:file2_path" as a file path with the first directory it steps into being, e.g., HEAD^:foo/. This will rarely exist so it generally gives an informative error message. (Note: @philh says that git diff commit1:file1_path file2_path works fine, but I haven't confirmed that myself.)

file1_path format: The paths given will be treated as relative to the repository's root. Absolute paths are not permitted, and relative paths must be explicit. For a concrete example; say your directory structure looks like the below, and your working directory is ~/repo/proj:

~/repo
  .git
  proj
    tests
      foo
        bar.sh
    utils
      baz
        quux.sh

If you are trying to compare HEAD^:(...)/bar.sh to HEAD:(...)/quux.sh, the only permissible paths for bar.sh are:

proj/tests/foo/bar.sh
./tests/foo/bar.sh

The explicit relative path with ./ works, but the more common implicit path tests/foo/bar.sh will not work. That version will sometimes fail silently - I think this is based on the format used in the other arguments but I'm not sure. Absolute paths will also not work; ~/repo/proj/tests/foo/bar.sh and /home/username/repo/proj/tests/foo/bar.sh will fail. AFAICT that will never fail silently.

"if you want to specify a commit for one file you must specify it for both" Not entirely - it seems that `git diff path1 foo:path2` doesn't work, but `git diff foo:path2 path1` does. — philh, Aug 03 '20 at 11:11

Git: How to diff two different files in different commits?

2 Answers2

Linked